Exposure control apparatus and method

• US 6,222,615 B1
• Filed: 12/02/1998
• Issued: 04/24/2001
• Est. Priority Date: 02/24/1993
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Suzuki, Kazuaki
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): Brown, Khaled
• Application Number:
  US09/203,348
• Time in Patent Office: 874 Days
• Field of Search: 355/67, 355/68, 355/69, 355/77, 355/71, 356/399, 356/400
• US Class Current: 355/68
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose
• CPC Class Codes: G03F 7/70566 Polarisation control
• CPC Class Codes: G03F 7/70583 Speckle reduction, e.g. coherence control or amplitude/wavefront splitting

Abstract

An apparatus has a pulse light source for emitting light pulses with varying light quantities, an illumination optical system for radiating the light pulses from the source onto a predetermined illumination region on a mask on which a transfer pattern is formed, and a projection optical system for projecting an image of the pattern onto a predetermined exposure region on a substrate, and which synchronously scans the mask and the substrate during the projection. The apparatus includes a measuring device for detecting intensities of the light pulses radiated onto the substrate during the scanning and measuring an integrated light quantity on each of a plurality of partial regions in the exposure region on the substrate on the basis of a detection signal of the intensities, wherein the partial regions are defined by a scanning speed of the photosensitive substrate and an oscillation interval of the light pulses. The apparatus further includes an adjusting device for adjusting an intensity of the next light pulse to be radiated onto the mask on the basis of a difference between a target integrated light quantity and the measured integrated light quantity on each of the partial regions when some light pulses are radiated onto the mask.

Claims

1. A scanning exposure method comprising:

moving each of a mask and a substrate independently to move the mask and the substrate synchronously;

emitting a plurality of light pulses during the synchronous movement of the mask and the substrate;

irradiating, during said synchronous movement, each of a plurality of regions on the substrate with at least one of the plurality of light pulses, wherein the plurality of regions are within an irradiation area of the light pulses, and integrated light quantities provided on said plurality of regions vary among said plurality of regions and wherein integrated numbers of pulses provided on the plurality of regions vary among the plurality of regions; and

adjusting, during synchronous movement, intensity of a next light pulse to be irradiated on the substrate, based on a light quantity of at least one of said plurality of light pulses.

2. A scanning exposure method according to claim 1, wherein said adjusting comprises:

detecting each of the light quantities of the plurality of light pulses emitted during said synchronous movement;

calculating the integrated light quantities based on the detected light quantities; and

adjusting the intensity of the next light pulse based on the calculated integrated light quantities.

3. A method according to claim 1, wherein the substrate is moved in a scanning direction during the synchronous movement and the plurality of regions are along the scanning direction within said irradiation area.

4. A scanning exposure method in which a pattern of a mask is transferred onto a substrate by moving the mask and the substrate synchronously, the method comprising:

determining a number N (N being an integer) of a plurality of light pulses for providing an appropriate exposure dose for each point on said substrate;

determining, based on the determined number N, at least one of a moving speed of said substrate, an oscillation frequency of the light pulses, and a width, in the substrate movement direction, of the light pulses incident on the substrate, wherein there are the number N of partial regions along the substrate movement direction within an irradiation area of the light pulses and wherein exposure doses provided on said partial regions vary among said partial regions during the synchronous movement and wherein integrated numbers of pulses provided on the partial regions vary among the partial regions.

5. A scanning exposure method according to claim 4, further comprising:

detecting a light quantity of each light pulse emitted during the synchronous movement; and

adjusting, during the synchronous movement, an intensity of a next light pulse to be irradiated on the substrate, based on the detected light quantity of at least one of the emitted light pulses.

6. A scanning exposure method according to claim 4, further comprising:

detecting a light quantity of each light pulse emitted during said synchronous movement;

calculating exposure doses of the plurality of said partial regions during said synchronous movement based on the detected light quantity; and

adjusting an intensity of a next light pulse to be irradiated on the substrate, based on the calculated exposure doses.

7. A scanning exposure method according to claim 4, wherein said number N is determined by taking into account at least one of variation of energy among the light pulses and smoothing of an interference pattern generated on said substrate.

8. A scanning exposure method in which a pattern of a mask is transferred onto a substrate while moving the mask and the substrate synchronously, the method comprising:

moving each of a mask and a substrate independently to move the mask and the substrate synchronously;

emitting a plurality of light pulses during the synchronous movement of the mask and the substrate;

irradiating each of a plurality of partial regions which are within an irradiation area of the light pulses on the substrate with at least one of the plurality of light pulses during said synchronous movement, wherein integrated light quantities provided on said plurality of partial regions vary among said plurality of partial regions and wherein integrated numbers of pulses provided on the plurality of partial regions vary among the plurality of partial regions; and

detecting, during said synchronous movement, a light quantity of at least one of said plurality of light pulses to control a subsequent scanning exposure operation.

9. A method according to claim 8, wherein the control of the subsequent scanning exposure operation includes a control of emission of a light pulse to be irradiated on the substrate.

10. A method according to claim 9, wherein the control of the emission of the light pulse includes an adjusting of intensity of the light pulse.

11. A method according to claim 9, wherein the control of the emission of the light pulse includes an adjusting of intensity of the next light pulse.

12. A method according to claim 11, wherein the adjusting of the intensity of the next light pulse is effected every time a light pulse is emitted.

13. A method according to claim 11, wherein the adjusting of the intensity of the next light pulse is effected by controlling a voltage applied to a light source which emits said next light pulse.

14. A method according to claim 8, wherein the substrate is moved in a scanning direction during the synchronous movement and the plurality of partial regions are along the scanning direction.

15. A method according to claim 14, wherein the plurality of partial regions are defined based on the distance which said substrate moves in said scanning direction during the interval of the emissions of light pulses.

16. A method according to claim 14, wherein an integer number of the plurality of partial regions are defined along the scanning direction.

17. A method according to claim 14, wherein an integrated light quantity in a partial region on one side, with respect to said scanning direction is larger than an integrated light quantity in a partial region on another side.

18. A method according to claim 8, wherein said plurality of light pulses comprises excimer laser light.

19. A method according to claim 8, wherein said detecting of the light quantity includes detecting of a light quantity of each of the plurality of light pulses.

20. A device manufacturing method which uses the method according to claim 8.

21. A scanning exposure method in which a pattern is formed on an object by moving the object relative to light pulses in a predetermined direction, the method comprising:

emitting the light pulses at a predetermined maximum oscillation frequency, and

adjusting moving speed of the object to provide an appropriate scanning exposure for the object with the light pulses emitted at the predetermined maximum oscillation frequency.

22. A method according to claim 21, wherein a width of said light pulses is constant with respect to said predetermined direction.

23. A method according to claim 21, wherein each point on said object is irradiated with an integer number of light pulses.

24. A method according to claim 21, wherein the number of light pulses with which each point on said object is irradiated is determined based on a variation in energy of the light pulses.

25. A method according to claim 21, wherein the number of light pulses with which each point on said object is irradiated is determined taking into account an influence of an interference pattern generated on said object.

26. A method according to claim 21, wherein said moving speed of the object is determined based on sensitivity of photosensitive material on said object.

27. A method according to claim 21, further comprising adjusting intensity of the light pulses.

28. A method according to claim 27, wherein the intensity of the light pulses is determined such that the moving speed of the object does not exceed a predetermined maximum speed.